Deep-sea trenches form when one tectonic plate subducts another underwater

Most volcanic activity occurs in submarine volcanoes on the seafloor

At divergent plate boundaries in mid-ocean ridges, volcanic activity produces new ocean crust as the seafloor spreads. These areas are home to underwater mountains with extensive biodiversity due to redirecting ocean currents and concentrating food for marine life.

When oceanic plates sink beneath tectonic ones, they can generate magma

At converging oceanic-continental plate boundaries, the subduction of the oceanic plate introduces seawater that reduces the melting temperature of the overlying mantle. This causes it to melt into less dense magma, which can rise to fuel more volcanic activity.

Mid-ocean ridges are underwater volcano systems where tectonic plates diverge

New ocean crust is formed at these ridges as magma rises from Earth’s mantle and fills the space between the spreading plates. The speed of divergence influences ridge shape, with slow spreads forming rugged valleys and fast spreading creating smooth, wide slopes.

Into the Mariana Trench

Located in the western Pacific Ocean, the Mariana Trench is the deepest known point on Earth. Its lowest point, known as Challenger Deep, is farther down than the height of Mount Everest by more than a mile. This 13-minute video discusses how the trench was formed, and the extreme conditions at the sea floor.

Tectonic earthquakes are caused by interactions of tectonic plates at fault zones

At these locations, plates slide past one another, deforming rock through friction as energy builds like a stretched rubber band. Volcanic eruptions, the collapse of subterranean caverns, or underground nuclear explosions can also cause earthquakes.

Some tectonic plates move faster than their underlying convection currents

Like a chain slipping off a ledge, as tectonic plates sink, their weight can pull the rest of the trailing plate forward, accelerating their movement. Plates can also break apart and fall, creating a suction effect that drives movement, resembling leaves following a passing car.

View examples of rift valleys, the product of surface divergent boundaries

At these boundaries, tectonic plates move apart, stretching and thinning Earth’s crust as long valleys are formed from smaller, interconnected valleys and troughs. Ongoing rifting and erosion can further sink the valley, becoming a rift lake if volcanic activity becomes inactive.

Tsunamis are caused by sudden seafloor shifts displacing water

Earthquakes of magnitude 7.0 with hypocenters within 100 km of the seafloor can vertically shift large sections of the seafloor significantly. This seismic activity is more commonly found in subduction zones, where an oceanic plate sinks beneath a continental one.

Slab pull and ridge push contribute to convection-driven oceanic crust movement

Through ridge push, after magma is projected up from the mantle, it cools and sinks, allowing gravity to help push older oceanic crust away. As this crust sinks into the mantle at deep-sea trenches, it pulls on the trailing crust behind it, accelerating ocean crust movement.

Explore case studies of each type of convergent plate boundary

At these boundaries, a collision of two oceanic plates produces a curved chain of volcanic islands, like those seen in the Caribbean. A continental-continental plate collision results in plates buckling upward, forming large mountain ranges.

Earth’s major tectonic plates make up 95% of its surface

Tectonic plates are pieces of Earth’s lithosphere, which consists of the crust and the solid, upper layer of the mantle. Segments of major plates can break and form minor or microplates, whose total number varies based on ongoing geological activity.

View a map of the world’s major earthquakes from 1956-2022

Such maps can help identify tectonic plate boundaries. The most significant earthquakes are characteristic of converging plates, such as those in the Circum-Pacific Belt and the Alpine-Himalayan Belt, where the Himalayas continue to grow.

Records of Earth's magnetic field on the seafloor validated plate tectonics

Matching glacial, fossil, and rock records, mountain ranges, and continental shapes across oceans was insufficient evidence for continental drift. Precise measurements of magnetic minerals on the ocean floor revealed seafloor spreading, which could only be explained by moving landmasses.

Explore the animals that populate the depths of the ocean, from fish and coral in the first few hundred feet, all the way down to the bottom of the Mariana Trench.

NASA explores Earth's deepest oceans to prepare for space

By studying extreme environments in Earth's hadal zone—the deepest part of the ocean —NASA tests technologies, probes life under crushing pressure, and gathers clues about potential oceans and possible life on worlds like Europa and Enceladus.

Underwater volcanoes significantly contributes to marine extinctions during the Triassic period

An analysis of ocean basins in the Tibetan Plateau helped identify three major periods of volcanism—250-248, 233-231, and 210-208 million years ago—which released significant amounts of greenhouse gases, altering ocean chemistry. The low-oxygen conditions may help explain half of Earth's Triassic extinctions.

Sinkholes form when underground cavities cause the surface above to collapse

These openings are typically carved by acidic water, which often forms in limestone-rich areas. However, leaking pipes, groundwater removal and extreme weather or geological activity increases the frequency of sinkhole appearances.

An interactive of the deep sea

How we know what’s deep inside the Earth, despite never traveling there

We'll likely never see the Earth's core, but we can make educated guesses about what it's like down there. Nearly as hot as the sun's surface and under impossibly high pressure, the inner Earths extreme conditions make it impossible to explore. Yet, seismic waves during earthquakes, volcanic eruptions, and light waves from the sun provide fascinating insights about our planet’s mantle, crust, and core.

Watch the destructive force of bottom trawling on marine ecosystems

Bottom trawling is a fishing method where a net is dragged along the seafloor to catch a species of interest. The process produces as much carbon dioxide yearly as global aviation and leaves trails of destruction large enough to be seen in space.

What is the Cascadia subduction zone?

A look at the Cascadia subduction zone, where the historical record suggests the Pacific Northwest is due for a devastating mega-earthquake in the coming years.

Remnants of another planet that helped form the moon may be beneath Earth's surface

Large mantle structures beneath Africa and the Pacific Ocean may be the buried remains of Thea, a large Mars-sized planet that collided with Earth. The theory is supported by isotopic evidence from volcanic and lunar rocks.

38 thought-provoking facts about the ocean

Coral produces its own sunscreen, tsunamis move at 500 miles per hour, one of the loudest sounds ever recorded came from an ice quake, and other interesting facts collected from sources such as National Geographic and NASA.

Waves off the coast of Nazaré, Portugal, can reach over 100 feet and are caused by the area's deep underwater canyon geography

Deep sea fish rely on a molecular strengthener to prevent being crushed

Trimethylamine N-oxide (TMAO) stabilizes hydrogen bonds and prevents water and proteins within organisms from being misshapen under immense pressure. Compounds called piezolytes protect cellular membranes from being crushed in regions like the Mariana Trench, where pressures are 1,100 times greater than surface atmospheric pressure.

The simplicity of immersed tube tunnels

Tunnels have traditionally bored holes through the earth below the water. On the other hand, immersed tube tunnels connect hollow, massive sections in trenches along the floor of the body of water. Each section is built on land, floated to the site, submerged, and connected. This method saves money by reducing expensive underground work, and it preserves an area's aesthetic appearance.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

The world's largest waterfall is in the ocean

In the Denmark Strait between Greenland and Iceland, a series of cataracts descend from 2,000 to 10,000 feet beneath the surface. The underwater waterfall is possible because cold water is denser than warm water and quickly sinks in the region.

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in terms of casualties, forces mobilized, and displacement of civilians.

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.